Interactive map details genetic mixing among humans centuries ago

Researchers from Oxford University and UCL (University College London) have created an interactive map which details the histories of genetic mixing between each of the 95 populations across Europe, Africa, Asia and South America spanning the last four millennia.

The study simultaneously identifies, dates and characterises genetic mixing between populations.

To do this, the researchers developed sophisticated statistical methods to analyse the DNA of 1490 individuals in 95 populations around the world. The work was chiefly funded by the Wellcome Trust and Royal Society.

"DNA really has the power to tell stories and uncover details of humanity's past," Dr Simon Myers of Oxford University's Department of Statistics and Wellcome Trust Centre for Human Genetics, and co-senior author of the study, said.

The powerful technique, christened 'Globetrotter', provides insight into past events such as the genetic legacy of the Mongol Empire. Historical records suggest that the Hazara people of Pakistan are partially descended from Mongol warriors, and this study found clear evidence of Mongol DNA entering the population during the period of the Mongol Empire.

Six other populations, from as far west as Turkey, showed similar evidence of genetic mixing with Mongols around the same time.

"What amazes me most is simply how well our technique works," lead author of the study Dr Garrett Hellenthal of the UCL Genetics Institute, said.

"Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing," he said.

The team used genome data for all 1490 individuals to identify 'chunks' of DNA that were shared between individuals from different populations. Populations sharing more ancestry share more chunks, and individual chunks give clues about the underlying ancestry along chromosomes.

As well as providing fresh insights into historical events, the new research might have implications for how DNA impacts health and disease in different populations.

The study is published in the journal Science.